1. Field of the Invention
The present invention relates to microporous metal-coated articles, preferably polytetrafluoroethylene (PTFE) articles, and a method for manufacturing the articles.
2. Background of the Invention
There has long been a need for a method of obtaining a high quality, adherent conductive metal coating on articles made from polytetrafluoroethylene (PTFE) polymer. However, the same qualities that have provided an impetus to use PTFE, namely, the relative inertness to a wide range of corrosive chemicals and low dielectric constant (good insulator) also have rendered this material extremely difficult to "metallize" using conventional metal plating techniques, and/or can result in products having poor and non-uniform metal coatings. Representative of the prior art concerning metal plating techniques for PTFE are the U.S. Pat. Nos. 4,150,171 to Feldstein and 4,021,314 to Dafter, Jr.
In addition to the problem of creating an adherent coating for PTFE, it is especially difficult to metallize the inner surface area of any porous structure. This characteristic is further affected by a reduction in the size of the porous openings, particularly with miniscule size pores in the order of 10 microns and even as small as 0.1 micron. Representative of prior art dealing with metal plating of porous electroplatable conductive bodies is U.S. Pat. No. 4,204,918 to McIntyre et al.
A recent invention (U.S. Pat. No. 3,953,566) provides a process for manufacturing microporous, high strength, shaped PTFE articles. These articles are characterized by a microstructure of nodes of substantially solid PTFE interconnected by fibrils. Products produced by this process should find wide acceptance in the industrial, medical, and electrical arts, for example, in industrial filter bag filtration art.